Noise suppressing throttling valve

ABSTRACT

A noise suppressing steam throttle valve comprises a pair of concentric seats and plugs, the inner seat and plug being disposed within the outer plug, and a plurality of ducts disposed in the outer plug for the steam to flow from upstream of the outer plug to upstream of the inner seat. Upon opening the valve, the inner plug moves upwardly allowing steam to flow through an increasing number of ducts as it opens, and opens fully before the outer plug moves off the outer seat. The ducts break up the steam flowing therethrough into small discrete jets which reduce the noise caused by the high pressure drop across the inner seat at low lifts. When the outer plug lifts off its seat the quantity of steam flowing through the ducts decreases until it approaches zero flow as the outer plug approaches its fully open position, thus minimizing the pressure drop across the fully open valve by allowing unrestricted flow across the outer seat.

[ Nov. 20, 1973 w NOISE SUPPRESSING THROTTLING VALVE PrirngryExaminer-Robert G. Nilson AttorneyA. T. Stratton, F. P. Lyle and F,Cristiano: 7

[5 7] ABSTRACT A noise suppressing steam throttle valve comprises a [75]Inventor: William C. Caldwell,Jr.,Br00khaven, Pa.

[73] Assi gnee: Westinghouse Electric Corporation,

7 li itisbi isia lei is .7 [22] Filed: Jan. 14, 1971 [21] Appl. No.:106,332

[52] US. Cl. l37/630.l5, 137/625.3 [51] Int. Cl Fl6k l/54 [58] Field ofSearch 137/630.11, 630.14, 137/630.15, 630.22, 630, 625.3

[56] References Cited UNITED STATES PATENTS 1,480,873 1/1924 Wagner...137/630.1l

938,491 11/1909 Knauf 137/63014 2,201,752 5/1940 Winberg 137/630 142,392,741 l/l946 Hurlburt 137/630.14 X 3,219,059 11/1965 Williams et al.137/625.3

pair of concentric seats and plugs, the inner seat and plug beingdisposed within the outer plug, and a plurality of ducts disposed in theouter plug for the steam to flow from upstream of the outer plug toupstream of the inner .seat. Upon opening the valve, the inner plugmoves upwardly allowing steam to flow through an increasing number ofducts as it opens, and opens fully before the outer plug moves off theouter seat. The ducts break up the steam flowing therethrough into smalldiscrete jets which reduce the noise caused by the high pressure dropacross the inner seat at low lifts. When the outer plug lifts off itsseat the quantity of steam flowing through the ducts decreases until itapproaches zero flow as the outer plug approaches its fully openposition, thus minimizing the pressure drop across the fully open valveby allowing unrestricted flow across the outer seat.

8 C Enn s-siev s Patented Nov. 20, 1973 3,773,085

2 Sheets-Sheet l FIG.|.

WITNESSES iNVENTOR MfiW William (3. Ccldwell,Jr.

Patented Nov. 20, 1973 2 Sheets-Sheet FIGS.

BACKGROUND OF THE INVENTION This invention relates to noise suppressingvalves and more particularly to a steam control valve having the noisesuppressor disposed in a two piece valve plug and having a positivelatching device which causes the two pieces of the plug to act in unisonduring emergency fast closing operations. With larger and largercapacity steam turbines the size of the throttling valve has increasedto handle the large quantity of steam flowing into the turbine. Suchvalves in order to control the steam flow to the turbine necessarilyoperate over a wide range of pressure drop, i.e., from about 2 percentwhen the valve is fully open to 100 percent when the valve is fullyclosed. Pressure drops in excess of 50 percent normally create extremelyhigh noise levels and vibration. Thus, it has been found necessary toprovide some device in the valve which will reduce the intensity of thenoise and vibration, however, the devices herebefore provided resultedin slightly higher pressure drops when the valve was fully open. Thisreduces the efficiency of the turbine and therefore is not desirable.

BRIEF SUMMARY OF THE INVENTION In general, a noise suppressingthrottling valve made in accordance with this invention comprises a bodyhaving inlet and outlet passages, a first valve seat disposed betweensaid inlet and outlet passages and providing a fluid passagewaytherebetween, a first valve plug having a central opening and an annularseating surface which registers with an annular seating surface on thefirst valve seat to stop the flow of fluid passing the seating surfacesfrom flowing from the inlet to the outlet passage, a second valve seatdisposed in the central opening of the first valve plug and a secondvalve plug disposed in the central opening and having an annular seatingsurface, which registers with an annular seating surface on the secondvalve seat to stop the flow of fluid passing the second seating surfacesfrom flowing from the central opening to the outlet passage. A pluralityof ducts are disposed in the first plug to provide conduits which areprogressively exposed as the second plug separates from its seat toallow fluid to flow from the inlet port into the central opening of thefirst plug. Such a valve further comprises a valve stem fastened to thesecond plug and has the first and second plug cooperatively associatedin such a manner that when opening the valve, the second plug lifts offthe second seat and opens fully before the first plug lifts off thefirst seat and when closing the valve, the first plug contacts the seatblocking the flow of fluid before the second plug begins to throttle thesteam flow.

BRIEF DESCRIPTION OF THE DRAWINGS The objects and advantages of thisinvention will become more apparent from reading the following detaileddescription in connection with the accompanying drawings, in which:

FIG. 1 is a fragmentary sectional view of a noise suppressing valve inits fully closed position incorporating the invention;

FIG. 2 is a fragmentary sectional view of the valve in its fully openposition; and

FIG. 3 is an enlarged fragmentary sectional view taken on line III-IIIof FIG. 2.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now to the drawings indetail, FIGS. 1 and 2 show a portion of a steam throttling valve made inaccordance with this invention. The valve comprises a body I havinginlet and outlet passages 3 and 5, and a first or outer valve seat 7,disposed between the inlet and outlet passages 3 and 5 and providing afluid or steam passageway therebetween. A first or outer valve plug 9has a central opening 1 l and an annular seating surface 13, whichregisters with an annular seating surface IS on the first valve seat 7,for blocking the flow of steam passing the seating surfaces 13 and 15.

A second or inner valve seat 17 and a second or inner valve plug 19 aredisposed in the central opening 11. The inner valve seat and plug 17 and19 each have annular seating surfaces 21 and 23, respectively, whichregister with each other for blocking the flow of steam from the centralopening 11 to the outlet passage 5. A- plurality of rows of ducts 25extend radially from the central opening 11 and provide throttlingconduits for steam to flow from the inlet passage 3 into the centralopening 11. As the inner plug moves away from its seat steam flowsthrough an increasing number of these ducts.

As shown in the drawings, a valve stem 27 is fastened to the second orinner plug 19 and is concentric with the axis of the first plug 9. Thecentral opening 11 of the outer plug 9, which receives the inner plug 19and valve stem 27, has three portions: a diverging portion 29, whichbegins to diverge adjacent the second or inner seat 17 and serves as adiffuser for steam flowing to the outlet passage 5; a centralcylindrical portion 31 having a relatively large diameter for receivingthe inner plug, which has a diameter only slightly smaller than thecylindrical portion; and a guide portion 33 through which the stem 27slides freely. The inner plug 19 is so disposed with respect to theouter plug 9 that it contacts and lifts the outer plug off its seat onlyafter the inner plug has reached the fully open position. FIGS. I and 2show a guideway 35 disposed in the valve body for aligning the seatingsurface 13 of the first plug 9 with the seating surface 15 of the firstseat 7.

As shown in FIG. 3, a latching device, generally indicated at 37,comprises a circumferential groove 39 in the valve stem 27, rods 41slidably mounted in radially extending bores 43 in the outer plug 9, andsprings 45 for biasing the rods 41 radially outwardly. Cam surfaces 47on the guideways 35, as shown in FIGS. 1 and 2, cause the rods 41 tomove inwardly and register with the circumferential groove 39 in thevalve stem 27 after the outer plug is moved off its seat by the stemrising beyond a position where the inner plug contacts the outer plug,thus locking the plugs together, so that they act in unison until theouter plug again approaches the seat 7 in a downward direction. The camsurfaces 47 allow the rods to move outwardly and disengage the groovesin the stem, so that the inner plug moves independently of the outerplug when the outer plug is seated.

Thus, upon opening of the valve, the inner plug 19 lifts off the innerseat 17 and steam flows from the inlet passage 3 through a progressivelygreater number of ducts 25 as the plug 19 rises. The ducts 2S throttlethe steam and break the flow into small discrete jets reducing the noiseintensity of the steam as it flows through the ducts, into the centralopening 11, across the seating surfaces 21 and 23 and out the outletpassage 5. As the valve stem continues to rise, the inner plug 19contacts the outer plug 9 adjacent the guide portion 33 and begins tolift the outer plug 9 off its seat 7. The cam surfaces 47 cause the rods41 to move inwardly and engage the groove 39 in the valve stem 27locking the inner and outer plugs so that they act in unison. As thestem 27 and the plug 9 continue to rise, the ducts 25 are moved out ofthe flow path of the steam, thus reducing the pressure drop across thevalve as it approaches its fully open position. Upon closing, the innerand outer plugs 19 and 9, respectively, move in unison until just beforethe outer plug 9 seats and then the cam surfaces 47 allow the rods 41 tomove outwardly, under the bias of the springs 45, unlatching the plugs.Once the outer plug 9 seats itself the inner plug 19 is moved by thestem 27 independently of the outer plug 9.

Having the plugs latched together when the valve is fully open, allowsthe stem to impart a closing force directly to the outer plug forclosing the valve quickly upon some malfunction of the turbine or itsassociated equipment. The inner plug may be lifted off its seat by arelatively small force compared to the force that would be required toinitially lift a plug, the diameter of the outer plug, sized for thetotal flow through the valve. By the time the outer plug is ready to belifted off its seat the pressure drop across the outer plug isconsiderably reduced, thus reducing the force required to lift the outerplug. There are no piston rings to gal] and leak in valves made inaccordance with this invention as there normally are in valves of thistype employing a single plug.

What is claimed is:

1. A noise suppressing throttle valve comprising a body having inlet andoutlet fluid passages;

a first valve seat disposed between said inlet and outlet passages andproviding a fluid passageway therebetween;

a first valve plug having a central opening and an annular seatingsurface which registers with an annular seating surface on said firstvalve seat to stop the flow of fluid passing said seating surfaces fromflowing from said inlet to said outlet passage;

a second valve seat disposed in said central opening of said first valveplug;

a second valve plug disposed in said central opening and having anannular seating surface which registers with an annular seating surfaceon said second valve seat to stop the flow of fluid passing said secondseating surface from flowing from said central opening to said outletpassage;

a plurality of elongated ducts having small cross sectional dimensionsrelative to their length disposed in the first plug to provide aplurality of discrete jets of fluid which reduce the intensity of thenoise produced by the fluid as it flows from said inlet passage to saidcentral opening; and

a valve stem fastened to said second plug;

the first and second plugs being cooperatively associated in such amanner that when opening said valve, said second plug comes off saidsecond seat and opens fully before said first plug comes off said firstseat, and when closing said valve, said first plug contacts said firstseat blocking the fluid flow between said first seating surfaces beforethe second plug begins to throttle the steam flow.

2. A valve as set forth in claim 1, further comprising means for lockingthe first and second plugs together so they act in unison, after saidfirst plug is moved off the first seat as the valve opens and remain solocked until the first plug approaches said first seat as the valvecloses.

3. A valve as set forth in claim 1 and further comprising acircumferential groove in the valve stem and latching means whichregister with said groove to latch the first and second plugs togetherafter said first plug is moved off the first seat, and which allows thesecond plug to move independently when the first plug approaches saidfirst seat.

4. A valve as set forth in claim 1 and further comprising guide meansfor aligning the seating surface of the first plug with the seatingsurface of the first seat.

5. A valve as set forth in claim 1 and further comprising guide meansfor aligning the first plug with the first seat, a circumferentialgroove in the valve stem, rods slidably mounted in radially extendingbores in said first plug, biasing means for urging the rods in aradially outward direction, and cam surfaces on the guide means whichcause said rods to register with said circumferential groove in thevalve stem after the first plug is moved off its seat causing the firstand second plugs to act in unison until the first plug approaches thefirst seat.

6. A valve as set forth in claim 1, wherein the ducts extend outradially from the central opening in the first plug.

7. A valve as set forth in claim 1 wherein there are a plurality of rowsof radially extending ducts disposed in said first plug to provide aprogressively increasing number of discrete jets of fluid as the secondplug moves away from its seat, and thereby minimize the noise producedby the fluid as it flows from the inlet passage to the central cavity.

8. A valve as set forth in claim 1, wherein the central opening isconcentric with the axis of the first plug and the central opening hasthree portions, a diverging portion which begins to diverge adjacent thesecond seat, a cylindrical portion having a relatively large diameterfor receiving the second plug, and a guide portion through which thestern slides freely.

1. A noise suppressing throttle valve comprising a body having inlet andoutlet fluid passages; a first valve seat disposed between said inletand outlet passages and providing a fluid passageway therebetween; afirst valve plug having a central opening and an annular seating surfacewhich registers with an annular seating surface on said first valve seatto stop the flow of fluid passing said seating surfaces from flowingfrom said inlet to said outlet passage; a second valve seat disposed insaid central opening of said first valve plug; a second valve plugdisposed in said central opening and having an annular seating surfacewhich registers with an annular seating surface on said second valveseat to stop the flow of fluid passing said second seating surface fromflowing from said central opening to said outlet passage; a plurality ofelongated ducts having small cross sectional dimensions relative totheir length disposed in the first plug to provide a plurality ofdiscrete jets of fluid which reduce the intensity of the noise producedby the fluid as it flows from said inlet passage to said centralopening; and a valve stem fastened to said second plug; the first andsecond plugs being cooperatively associated in such a manner that whenopening said valve, said second plug comes off said second seat andopens fully before said first plug comes off said first seat, and whenclosing said valve, said first plug contacts said first seat blockingthe fluid flow between said first seating surfaces before the secondplug begins to throttle the steam flow.
 2. A valve as set forth in claim1, further comprising means for locking the first and second plugstogether so they act in unison, after said first plug is moved off thefirst seat as the valve opens and remain so locked until the first plugapproaches said first seat as the valve closes.
 3. A valve as set forthin claIm 1 and further comprising a circumferential groove in the valvestem and latching means which register with said groove to latch thefirst and second plugs together after said first plug is moved off thefirst seat, and which allows the second plug to move independently whenthe first plug approaches said first seat.
 4. A valve as set forth inclaim 1 and further comprising guide means for aligning the seatingsurface of the first plug with the seating surface of the first seat. 5.A valve as set forth in claim 1 and further comprising guide means foraligning the first plug with the first seat, a circumferential groove inthe valve stem, rods slidably mounted in radially extending bores insaid first plug, biasing means for urging the rods in a radially outwarddirection, and cam surfaces on the guide means which cause said rods toregister with said circumferential groove in the valve stem after thefirst plug is moved off its seat causing the first and second plugs toact in unison until the first plug approaches the first seat.
 6. A valveas set forth in claim 1, wherein the ducts extend out radially from thecentral opening in the first plug.
 7. A valve as set forth in claim 1wherein there are a plurality of rows of radially extending ductsdisposed in said first plug to provide a progressively increasing numberof discrete jets of fluid as the second plug moves away from its seat,and thereby minimize the noise produced by the fluid as it flows fromthe inlet passage to the central cavity.
 8. A valve as set forth inclaim 1, wherein the central opening is concentric with the axis of thefirst plug and the central opening has three portions, a divergingportion which begins to diverge adjacent the second seat, a cylindricalportion having a relatively large diameter for receiving the secondplug, and a guide portion through which the stem slides freely.